Answer
$\text{add}$; $25$
Work Step by Step
General strategy to complete the square of a quadratic equation $ax^2+bx+c$ is to add the value of $\left(\dfrac{b}{2}\right)^2$.
Thus, to complete the square of the given polynomial, we will have to add $\left(\dfrac{10}{2}\right)^2=5^2=25$.
